I think the android version needs a recompilation in 3.1, bindings changed a bit and there was a point where the build was broken, so i’m not sure if it is up to date.
I’ve built a script that automatically compile osx, windows and linux versions on travis but i’m not very familiar with compilation for android so i haven’t added the support yet.
Mhh, well… i’ve updated bullet to the last version (2.86) anyway, I haven’t push the changes yet (i’m testing to be sure it’s working) when I’ll do it we’ll see if it works.